Atomic Spectra Research Articles

Design and fabrication of a dual laser Raman spectrometer with a single one-dimensional CCD detector

The combination of two spectrometers in dual-laser Raman devices without the need for moving parts represents a significant advancement. This study focuses on design and fabrication of a dual spectrometer with no moving components, allowing data to be gathered using a single detector. This instrument consists of two Czerny–Turner optical arrangements which is symmetrically merged. Dual spectrometer single detector has two light inputs, each of them, concentrating the light separately on a one linear charge-coupled device detector through two independent optical paths. In this innovative spectrometer design, no optical moving parts are used, and therefore, the wavelength displacement error in repeating the spectroscopic experiment is zero. The independent nature of the optical paths enables the optimization of each spectrometer arrangement without affecting the other. The final spectrometer has a spectral resolution of 4.6 and 6.11 cm− 1 for Full Width at Half Maximum across the wavelength ranges of 532 to 708 nm and 784.65 to 1100 nm, respectively. Switching between the two different acquisition setups can be done seamlessly and quickly, with the ability to record approximately 2000 spectra per second. Standard neon and mercury-argon lamps’ atomic radiation spectra, along with Raman scattering data from a cyclohexane standard sample, were successfully recorded using laser wavelengths of 532 nm and 784.65 nm.

Enhanced Control of Single-Molecule Emission Frequency and Spectral Diffusion.

The Stark effect provides a powerful method to shift the spectra of molecules, atoms, and electronic transitions in general, becoming one of the simplest and most straightforward ways to tune the frequency of quantum emitters by means of a static electric field. At the same time, in order to reduce the emitter sensitivity to charge noise, inversion symmetric systems are typically designed, providing a stable emission frequency with a quadratic-only dependence on the applied field. However, such nonlinear behavior might be reflected in correlations between the tuning ability and unwanted spectral fluctuations. Here, we provide experimental evidence of this trend using molecular quantum emitters in the solid state cooled down to liquid helium temperatures. We finally combine the electric field generated by electrodes, which is parallel to the molecule's induced dipole, with optically excite long-lived charge states acting in the perpendicular direction. Based on the anisotropy of the molecule's polarizability, our two-dimensional control of the local electric field allows us not only to tune the emitter's frequency but also to sensibly suppress the spectral instabilities associated with field fluctuations.

Acoustic Drift: Generating Helicity and Transferring Energy

This article studies the general properties of the Stokes drift field. This name is commonly used for the correction addedto the mean Eulerian velocity for describing the averaged transport of the material particles by the oscillating fluid flows. Stokes drift is widely known mainly in connection with another feature of oscillating flows known as steady streaming, which has been and remains the focus of a multitude of studies. However, almost nothing is known about Stokes drift in general, e.g., about its energy or helicity (Hopf’s invariant). We address these quantities for acoustic drift driven by simple sound waves with finite discrete Fourier spectra. The results discover that the mean drift energy is partly localized on a certain resonant set, which we have described explicitly. Moreover, the mean drift helicity turns out to be completely localized on the same set. We also present several simple examples to reveal the effect of the power spectrum and positioning of the spectral atoms. It is revealed that tuning them can drastically change both resonant and non-resonant energies, zero the helicity, or even increase it unboundedly.

Chemical and Acoustical Mixed-Mapping of Geological Materials from Laser-Induced Plasmas: A Comprehensive Approach to Differentiate Mineral Phases.

The acoustic wave produced alongside laser-induced plasmas can be used in conjunction with the recorded atomic spectra of plasma emission to expand the physicochemical information acquired from a single inspection event. Among the most interesting uses of acoustic information is the differentiation of mineral phases with similar optical responses coexisting in geological targets. In addition, laser-induced plasma acoustics (LIPAc) can provide data related to the inspected material's hardness, density, and compactness. In this paper, we present a dual acoustic-optic laser-based strategy for the generation of high-resolution surface images of mineral samples. By combining simultaneous multimodal LIBS (laser-induced breakdown spectroscopy) and LIPAc spectral data from laser-induced plasmas, we explore the mineralogical composition of rocks embedded in resin matrixes to distinguish their chemical composition as well as their crystal phases based on physical changes caused by the different spatial arrangements of the constituent atoms. The multispectral polyhedron created by merging singular optical maps, one per detected elements, and the coincidental acoustic map enhance the distinction between regions present within the matrix of a host rock as compared to the differentiation yielded by each technique when used separately. The chemical information guides the composition of the mineral phases in the host rock. Then, the physical information obtained from acoustics may reinforce the identification of the detected mineral phase, draw the geological history of the inspected section, and showcase possible transformations, mainly of polymorphic nature. To test the combination proposed herein, we also inspected a septarian nodule featuring an ensemble of mineral phases with different origins. Mixed optical and acoustic responses from laser-produced plasmas of this complex sample allowed us to obtain more specific information. This approach constitutes a reliable and high-throughput tool for studying the surface of geological samples, which can substantially supplement well-established techniques for mineralogical analysis such as Raman spectroscopy and X-ray diffraction.

Strong noninertial radiative shifts in atomic spectra at low accelerations

Despite numerous proposals investigating various properties of accelerated detectors in different settings, detecting the Unruh effect remains challenging due to the typically weak signal at achievable accelerations. For an atom with frequency gap ω0, accelerated in free space, significant acceleration-induced modification of properties like transition rates and radiative energy shifts requires accelerations of the order of ω0c. In this paper, we make the case for a suitably modified density of field states to be complemented by a judicious selection of the system property to be monitored. We study the radiative energy-level shift in inertial and uniformly accelerated atoms coupled to a massless quantum scalar field inside a cylindrical cavity. Uniformly accelerated atoms experience thermal correlations in the inertial vacuum, and the radiative shifts are expected to respond accordingly. We show that the noninertial contribution to the energy shift can be isolated and significantly enhanced relative to the inertial contribution by suitably modifying the density of field modes inside a cylindrical cavity. Moreover, we demonstrate that monitoring the radiative energy shift, as compared to transition rates, allows us to reap a stronger purely noninertial signal. We find that a purely noninertial radiative shift as large as 50 times the inertial energy shift can be obtained at small, experimentally achievable accelerations (a∼10−9ω0c) if the cavity’s radius R is specified with a relative precision of δR/R0∼10−7. Given that radiative shifts for inertial atoms have already been measured with high accuracy, we argue that the radiative energy-level shift is a promising observable for detecting Unruh thermality with current technology. Published by the American Physical Society 2024

Microwave field sensor based on cold cesium Rydberg three-photon electromagnetically induced spectroscopy

Abstract We present the electromagnetically induced transparency (EIT) spectra of cold Rydberg four-level cascade atoms consisting of the 6S1/2 → 6P3/2 → 7S1/2 → 60P3/2 scheme. A coupling laser drives the Rydberg transition, a dressing laser couples two intermediate levels and a weak probe laser probes the EIT signal. We numerically solve the Bloch equations and investigate the dependence of the probe transmission rate signal on the coupling and dressing lasers. We find that the probe transmission rate can display an EIT or electromagnetically induced absorption (EIA) profile, depending on the Rabi frequencies of the coupling and dressing lasers. When we increase the Rabi frequency of the coupling laser and keep the Rabi frequency of the probe and dressing laser fixed, flipping of the EIA to EIT spectrum occurs at the critical coupling Rabi frequency. When we apply a microwave field coupling the transition 60P3/2 → 61S1/2, the EIT spectrum shows Autler–Townes splitting, which is employed to measure the microwave field. The theoretical measurement sensitivity can be 1.52 × 10−2 nV⋅cm−1⋅Hz−1/2 at the EIA–EIT flipping point.

A Rydberg-Bohr-de Broglie Algebraic Model of Hydrogen Atoms

Bohr ignored the electromagnetic interaction of moving charges in atoms and only considered Coulomb forces, thus encountering half frequency difficulties. This article considers the Lorentz force to make the classical Bohr model consistent with modern quantum theory, uses de Broglie's standing wave principle instead of Bohr's quantization assumption, derives the energy level formula for hydrogen atoms, and explains the radiation mechanism of hydrogen atomic spectra. The hydrogen atom in a spectral tube emits a photon wave train during one free path, and the wavelength of the photon is the eigen wavelength of its wave train. The head wavelength of the wave train is four thirds of its eigen wavelength, and the tail wavelength of the wave train is two-thirds of its eigen wavelength.

To the Theory of the Lamb Shift in the Relativistic Hydrogen Atom

Radiative corrections which remove the accidental degeneracy in the spectrum of the relativistic hydrogen atom and lead to the modification of the Coulomb law, are calculated within the novel approach, based on the exact solution of the Dirac equation with the Coulomb potential. The energy spectrum of the hydrogen atom is obtained with account for these corrections, and the Lamb shift is calculated for the lowest energy states.

Distribution of angular momenta ML and MS in non-relativistic configurations: statistical analysis using cumulants and Gram-Charlier series

Abstract The distributions P(ML,MS) of the total magnetic quantum numbers ML and MS for N electrons of angular momentum l, as well as the enumeration of LS spectroscopic terms and spectral lines, are crucial for the calculation of atomic structure and spectra, in particular for the modeling of emission or absorption properties of hot plasmas. However, no explicit formula for P(ML,MS) is known yet. In the present work, we show that the generating function for the cumulants, which characterize the distribution, obeys a recurrence relation, similar to the Newton-Girard identities relating elementary symmetric polynomials to power sums. This enables us to provide an explicit formula for the generating function. We also analyze the possibility of representing the P(ML,MS) distribution by a bi-variate Gram-Charlier series, which coefficients are obtained from the knowledge of the exact moments of P(ML,MS). It is shown that a simple approximation is obtained by truncating this series to the first few terms, though it is not convergent.

DFT study of electron energy loss spectra of sulfur in Janus MoSSe, MoSTe, WSSe and WSTe monolayers

In this paper, electronic properties of Janus MSX monolayers (M = Mo, W; X = Se or Te), including electron energy loss near edge structures (ELNES), as K and [Formula: see text] edge spectra of sulfur atoms, have been calculated using a full potential scheme and the augmented plane wave plus local orbitals (APW+lo) method in the framework of density functional theory (DFT). Due to the lack of experimental results, the obtained spectra are compared with the corresponding spectra of MoS2 monolayer. The band structure analysis shows that the Janus MoSSe and WSSe monolayers are direct bandgap semiconductors, while the Janus MoSTe and WSTe monolayers are indirect bandgap semiconductors. In comparison to MoS2, the main structures of the K edge ELNES spectra of sulfur atoms in Janus monolayers occur at lower energies, due to the structural change and increased bond length. The relative reduction of intensities in the main structures predicts the possibility of reducing the number of partial densities of states (PDOS), that is, the reduced p PDOS for the K edge in the corresponding energy range. In the K ([Formula: see text] edge ELNES spectra of the sulfur atom in Janus monolayers and MoS2 monolayers, the main structures are due to the electron transfer to the unoccupied [Formula: see text] and [Formula: see text] states (3s of sulfur and 4d states of the transition metal).

Development of an atomic spectra research platform based on a 30-keV electron beam ion trap.

Electron Beam Ion Traps (EBITs) serve as efficient tools for producing and studying highly charged ions. In response to the diagnostic requirements of upcoming magnetic confinement fusion devices, a medium-energy atomic spectra research platform based on a compact EBIT is developed. This platform achieves a central magnetic field of up to 1.0T, with electron beam currents reaching 20 mA and electron energies up to 30keV, similar to the electron temperature on fusion reactors. The developed atomic spectra platform successfully provided spectral data for elements such as argon, xenon, iron, and tungsten. This platform stands as a valuable asset for advancing research in nuclear fusion, particularly concerning impurity spectroscopic diagnostics.

Preparation of copper glycinate and study of its effect on the germination of winter barley seeds

We analyzed the encrustation of winter barley seeds, which includes its preliminary treatment with cuprum glycinate, with the purpose of increasing yield and biochemical indicators of grain, and also improving the ecological condition of the soil. The objective of the research was to select methods for the synthesis of cuprum glycinate, study its chemical composition and the possibility of using this compound as a chelated micro-fertilizer for pre-sowing encrustation of winter barley seed as part of a tank mixture. Two well-known synthesis methods were used to obtain cuprum glycinate. The first method was the interaction between CuO with a solution of glycine during heating, during which pink metallic copper inclusions were noticed in the mixture of reaction products. It was found that it is expedient to synthesize the glycine complex of cuprum by the reaction of a suspension of Cu2CO3(OH)2 with glycine during heating (the yield is 97%), since a complex compound Cu(NH2CH2COO)2•H2O of sufficient purity is formed. The composition of the synthesized substance and the confirmation of the formula of the compound Cu(NH2CH2COO)2•H2O were obtained by determining the infrared and the atomic absorption spectrum of the aqueous solution. Based on the obtained differences in the atomic absorption spectra of the synthesized copper sulfate and copper glycinate the formation of the latter was confirmed. The IR spectrum confirms the formula of the complex compound and the formation of strong covalent bonds between the metal cation and the ligands. The study of the effect of cuprum glycinate on the germination of winter barley Tutankhamun seeds was carried out in comparison with the similar effect of a complex compound of cuprum with ethylenediaminetetraacetate. The study of the influence of cuprum glycinate on the germination of winter barley revealed positive results in which the germination exceeded the control by 9–27%. Winter barley seeds treated with distilled water served as a control. Treatment of winter barley seeds with an aqueous solution of cuprum glycinate in the amount of 20 g of cuprum per 1 ton of grain led to better germination than pre-treatment of seeds with a twice concentrated corresponding solution. Treatment with a complex compound of copper with ethylenediaminetetraacetate had no significant effect on the germination and characteristics of sprouts. The results of laboratory studies confirmed the feasibility of using complex compounds of biometal copper with organic chelating ligands as microfertilizers for pre-sowing seed encrustation, as they have high stability and sufficient solubility in water, are non-toxic, are better absorbed by plants and are considered cost-effective and environmentally safe.

Continuum spectrum of atomic lithium in a magnetic field of white dwarfs

ABSTRACT This paper reports on computational results of continuum spectra of atomic lithium in white-dwarf-strength magnetic fields. The adiabatic-basis-expansion method with R-matrix propagation has been used to study photoionization of magnetized alkali metal atoms. The R-matrix propagation technique and the two-dimensional matching scheme were utilized to obtain wavefunctions of the continuum states. Cross-sections of photoionization are calculated for lithium atoms in magnetic fields. Continuum spectra for its various bound-free transitions in magnetic white dwarf stars are presented as a function of field strengths ranging from 11.75 to 117.50 MG. Comparison is made between continuum spectra of diamagnetic hydrogen and lithium atoms. The comparison shows good agreement or remarkable difference for final continuum states with different symmetries in the photoionization processes concerned. A detailed analysis has been performed to understand the obtained results. The good agreement displayed manifests the reliability of the extended adiabatic-basis-expansion method. This method is suited to produce a large number of photoionization cross-section data for alkali metal atoms in a strong magnetic field, and therefore can serve as a tool to simulate continuum spectra observed in the atmospheres of magnetic white dwarfs with alkali metal atoms.

In silico bioactivity prediction of proteins interacting with graphene-based nanomaterials guides rational design of biosensor

Graphene-based nanomaterials have attracted significant attention for their potentials in biomedical and biotechnology applications in recent years, owing to the outstanding physical and chemical properties. However, the interaction mechanism and impact on biological activity of macro/micro biomolecules still require more concerns and further research in order to enhance their applicability in biosensors, etc. Herein, an integrated method has been developed to predict the protein bioactivity performance when interacting with nanomaterials for protein-based biosensor. Molecular dynamics simulation and molecular docking technique were consolidated to investigate several nanomaterials: C60 fullerene, single-walled carbon nanotube, pristine graphene and graphene oxide, and their effect when interacting with protein. The adsorption behavior, secondary structure changes and protein bioactivity changes were simulated, and the results of protein activity simulation were verified in combination with atomic force spectrum, circular dichroism spectrum fluorescence and electrochemical experiments. The best quantification alignment between bioactivity obtained by simulation and experiment measurements was further explored. The two proteins, RNase A and Exonuclease III, were regarded as analysis model for the proof of concept, and the prediction accuracy of protein bioactivity could reach up to 0.98. The study shows an easy-to-operate and systematic approach to predict the effects of graphene-based nanomaterials on protein bioactivity, which holds guiding significance for the design of protein-related biosensors. In addition, the proposed prediction model is not limited to carbon-based nanomaterials and can be extended to other types of nanomaterials. This facilitates the rapid, simple, and low-cost selection of efficient and biosafe nanomaterials candidates for protein-related applications in biosensing and biomedical systems.

Line identification of atomic and ionic spectra of Holmium in the near infrared spectral range from 700 nm to 1750 nm

The aim of the study is to extend the list of spectral lines of atomic and single ionized holmium (Ho) into the near infrared wavelength range up to 1750 nm. Spectra of a Ho hollow cathode discharge lamp with neon or argon as buffer gases have been measured with a Fourier Transform spectrometer in different spectral ranges. In total, the range from 700 nm to 1750 nm i.e. from 5710cm−1 to 14280cm−1 has been covered. A total of almost 800 spectral lines were detected. Based on the known energy levels of atom and ion Ho, 589 lines could be classified as Ho I transitions and 31 lines as Ho II transitions. The remaining 171 lines could mostly be classified as different Ho I or Ho II, based on different signal-to-noise ratios in spectra measured with different buffer gases. In the wavelength range from 1200 nm to 1750 nm, a list of Ho lines is presented for the first time. In the wavelength range from 700 nm to 1200 nm 216 lines had not been listed in literature up to now.

Elucidating atomic emission and molecular absorption spectra using a basic CD spectrometer: a pedagogical approach for secondary-level students

Abstract Spectroscopy has held a pivotal role in advancing our comprehension of chemistry, dating back to its inception by Robert Bunsen and Gustav Kirchhoff. Nonetheless, access to advanced spectrometers remains restricted, particularly in high schools within developing nations. In this laboratory experiment, students were guided to fashion a spectrometer using reusable materials. This uncomplicated contrivance facilitated the exploration of emission and absorption spectroscopy, acquainting students with atomic spectra marked by electronic transitions, yielding line spectra. Conversely, molecules display not solely electronic transitions, but also vibrational and rotational shifts within chemical bonds, culminating in band spectra. Mobile phone cameras were enlisted as detectors. Captures of sodium and copper atoms emitting light in the course of a flame test, as well as depictions of molecular entities (copper sulphate pentahydrate and potassium permanganate aqueous solutions) absorbing light, were transmuted into the RGB (Red-Green-Blue) color model channels. The learning outcomes exhibited that 86 % of the students successfully discerned between an atomic spectrum and a molecular spectrum. Furthermore, 93 % of the students indicated that the incorporation of mobile devices in fostering scientific comprehension effectively seized their attention, resulting in heightened levels of engagement.

Phosphoric acid-activated metakaolin-based geopolymer: Optimizing P/A molar ratio to solidify Cs+ and Sr2+ in nuclear waste

Phosphoric Acid-activated Metakaolin-based Geopolymer (PAMG) is an efficient solidified material. This paper reports the effect of the H3PO4 to Al2O3 (P/A) molar ratio on the hydration, phase assemblage, morphology, and compressive strength of PAMG and the solidification of simulated radionuclides Sr and Cs by PAMG. The hydration behavior and microstructure of PAMG were investigated using isothermal calorimetry, X-ray diffraction (XRD), and scanning electron microscope (SEM). The impacts of Cs and Sr on the leaching behavior and microstructure of PAMG were assessed using atomic absorption spectrum (AAS), SEM, and energy dispersion spectrum (EDS). The results indicate that the compressive strength of PAMG increases and then decreases as the P/A ratio increases. The highest compressive strength reaching 98.1 MPa after 28 days of curing, was observed at a P/A molar ratio of 1.8. The addition of Cs and Sr resulted in a decrease in the compressive strength of PAMG, with Sr showing a more significant reduction in PAMG's compressive strength. However, PAMG still exhibited a high efficiency in solidifying simulated nuclides Cs and Sr, with 42 days leaching rates of 3.7 × 10−5 cm/d and 5.0 × 10−6 cm/d, respectively. These results indicate the huge potential of PAMG in solidifying nuclides.

JARVIS-Leaderboard: a large scale benchmark of materials design methods

Lack of rigorous reproducibility and validation are significant hurdles for scientific development across many fields. Materials science, in particular, encompasses a variety of experimental and theoretical approaches that require careful benchmarking. Leaderboard efforts have been developed previously to mitigate these issues. However, a comprehensive comparison and benchmarking on an integrated platform with multiple data modalities with perfect and defect materials data is still lacking. This work introduces JARVIS-Leaderboard, an open-source and community-driven platform that facilitates benchmarking and enhances reproducibility. The platform allows users to set up benchmarks with custom tasks and enables contributions in the form of dataset, code, and meta-data submissions. We cover the following materials design categories: Artificial Intelligence (AI), Electronic Structure (ES), Force-fields (FF), Quantum Computation (QC), and Experiments (EXP). For AI, we cover several types of input data, including atomic structures, atomistic images, spectra, and text. For ES, we consider multiple ES approaches, software packages, pseudopotentials, materials, and properties, comparing results to experiment. For FF, we compare multiple approaches for material property predictions. For QC, we benchmark Hamiltonian simulations using various quantum algorithms and circuits. Finally, for experiments, we use the inter-laboratory approach to establish benchmarks. There are 1281 contributions to 274 benchmarks using 152 methods with more than 8 million data points, and the leaderboard is continuously expanding. The JARVIS-Leaderboard is available at the website: https://pages.nist.gov/jarvis_leaderboard/

Emission Spectra of Uranium Particulates at High Temperature.

The emission spectrum of micron-scale uranium particulates at high temperatures in the ultraviolet, visible, and near-infrared spectral regions is investigated using a heterogeneous shock tube. Temperatures from 3000 to 9000 K are characterized in an inert argon environment and with incremental amounts of added oxygen. Atomic line spectra do not emerge above the continuum emission spectrum until between 4500 and 5000 K in pure argon, and 6100 and 6600 K in 1% oxygen. For 5% oxygen, however, the threshold for atomic emission drops below 3800 K. Uranium monoxide molecular emission in the strongest visible band at 595.4 nm is not observed at any condition. Uncertainties in particle temperature determination in high-temperature shock tube environments are discussed, and limitations to such measurements are presented, such as those from experimental factors such as the powder loading method and expected detection limits of uranium species in relevant conditions.

Evaluation of plasma parameters’ impact on MRR and surface roughness in plasma polishing of fused silica: An investigation of surface characterization

Advanced fabrication methods with high efficiency are needed to meet the rising demand for precision optical components. This study proposes a plasma-based isotropic polishing method to remove fused silica's surface defects and subsurface damaged layers. Hence, a medium-pressure plasma process is developed to serve this purpose. The qualitative analysis of the plasma and atom emission spectrum explores the plasma generation and scattering of the activated fluorine (F*) radicals inside the plasma chamber. Material removal rate (MRR) and surface roughness variations with different total pressures of 5–30 mbar and substrate dimensions (i.e., varying length between 5 and 45 mm with fixed width and thickness of 5 and 2 mm) at fixed process parameters, i.e., radio-frequency power of 80 W, pressure ratio of 1:1, gas composition of 90:10, have been investigated. The highest and lowest MRR, i.e., 0.039 mm3/min and 0.0061 mm3/min, are achieved at 5 and 30 mbar total pressures on substrates having lengths 45 and 5 mm, respectively. The highest and lowest percentage change in surface roughness observed are 86.4 % and 17.1 % at 5 mbar and 30 mbar for substrates with 5 and 45 mm lengths, respectively. Surface morphology analysis shows the micro-cracks are reduced after plasma processing. The presence of elements, i.e., F and C, through EDX analysis, confirms the reactions on the plasma processed surface. Moreover, The XPS findings demonstrated that minimal radicals could be incorporated onto the fused silica surface during He/O2/SF6 plasma processing. At lower pressure, the surface roughness value increases due to the increased excitation and ionization rate caused by more interaction between the fluorine and surface atoms. The MRR increases with substrate dimension with constant pressure. Larger substrate dimensions result in increased MRR at lower pressure.